The proposed research is an outgrowth of prior work on the varied functions of punishment in discrimination learning, in particular, punishment's function as a "distinctive cue" which can facilitate performance even when administered for the rewarded response (shock- right training). In a recent extension of this work focusing on conditioned punishment, Pavlovian aversive conditioning was used to impart neutral stimuli with "acquired distinctiveness," e.g., through conditioned fear and its feedback component. This research has shown that a conditioned fear excitor (CS plus) for the food-rewarded response (fear-right training) will facilitate performance, in contrast to the suppression observed with a CER procedure, and conversely, that a conditioned fear inhibitor (CS minus) for the rewarded response will retard performance. Because these effects are exactly reversed when the CSs are administered for the non-rewarded response, they suggest that a CS has the primary function of signaling the occurrence (CS plus) or nonoccurrence (CS minus) of one type of reinforcer (e.g., shock) and that such a function can be readily transmuted in the context of a different reinforcer (e.g., food) to signal the presence or absence of the new reinforcer. Thus, depending upon the relation of its general signaling property to the presence or absence of reward, an aversive CS will functionally act as either a conditioned reinforcer (reward) or a conditioned punisher. The proposed research will assay the relationship of the general signaling and affective (aversive-appetitive) properties of a CS by systematically investigating those conditions under which aversive CSs either facilitate or retard performance in appetitive discrimination learning. Such research will be addressed to (a) the parameters of Pavlovian aversive conditioning, (b) the conditions of appetitive discrimination training, and (c) their interrelationship, and will be extended to include a CER methodology.